Cap for a flask



FIG. 1 is a perspective view of the top, front and left side of a cap for a flask showing our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational view thereof; and,

FIG. 6 is a top plan view thereof.

The elements shown in broken lines are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a cap for a flask, as shown and described. 